Add external Bootsnap cache inputs

[rafaelfranca]

Require Hooks source transforms can depend on external libraries or configuration. The existing version_hash= API sets one complete, static key and replaces the automatic hook key. For example:

RequireHooks::Bootsnap.version_hash = Parser::VERSION RequireHooks.source_transform do |_path, source|
  source.gsub("...", options_digest)
end

If options_digest changes while Parser::VERSION stays the same, Bootsnap reuses the old transformed entry because version_hash= does not include the transform option. A second version_hash= assignment would instead discard the first dependency.

Applications can register both inputs with:

RequireHooks::Bootsnap.add_version_hash do
  "parser-#{Parser::VERSION}-#{options_digest}"
end

Require Hooks evaluates each callable when it computes the key, hashes each contribution, and combines all contributions with the hook configuration. It then isolates transformed entries with Bootsnap compiler namespaces on modern Bootsnap and versioned cache directories on older versions.

Checklist

• I've added tests for this change
• I've added a Changelog entry
• I've updated a documentation

[palkan]

@rafaelfranca Please, let me know if you want me to publish a new release or there is more Bootsnap-related expected

[rafaelfranca]

This is the last one. Feel free to make a release. 0.5.0 is already good enough for us, but this will make sure our caches aren't reused when our transformation library changes

[palkan]

Great! v0.5.1 is on its way.